drivers/cpufreq/s3c64xx-cpufreq.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright 2009 Wolfson Microelectronics plc
   4  *
   5  * S3C64xx CPUfreq Support
   6  */
   7
   8 #define pr_fmt(fmt) "cpufreq: " fmt
   9
  10 #include <linux/kernel.h>
  11 #include <linux/types.h>
  12 #include <linux/init.h>
  13 #include <linux/cpufreq.h>
  14 #include <linux/clk.h>
  15 #include <linux/err.h>
  16 #include <linux/regulator/consumer.h>
  17 #include <linux/module.h>
  18
  19 static struct regulator *vddarm;
  20 static unsigned long regulator_latency;
  21
  22 struct s3c64xx_dvfs {
  23         unsigned int vddarm_min;
  24         unsigned int vddarm_max;
  25 };
  26
  27 static struct s3c64xx_dvfs s3c64xx_dvfs_table[] = {
  28         [0] = { 1000000, 1150000 },
  29         [1] = { 1050000, 1150000 },
  30         [2] = { 1100000, 1150000 },
  31         [3] = { 1200000, 1350000 },
  32         [4] = { 1300000, 1350000 },
  33 };
  34
  35 static struct cpufreq_frequency_table s3c64xx_freq_table[] = {
  36         { 0, 0,  66000 },
  37         { 0, 0, 100000 },
  38         { 0, 0, 133000 },
  39         { 0, 1, 200000 },
  40         { 0, 1, 222000 },
  41         { 0, 1, 266000 },
  42         { 0, 2, 333000 },
  43         { 0, 2, 400000 },
  44         { 0, 2, 532000 },
  45         { 0, 2, 533000 },
  46         { 0, 3, 667000 },
  47         { 0, 4, 800000 },
  48         { 0, 0, CPUFREQ_TABLE_END },
  49 };
  50
  51 static int s3c64xx_cpufreq_set_target(struct cpufreq_policy *policy,
  52                                       unsigned int index)
  53 {
  54         struct s3c64xx_dvfs *dvfs;
  55         unsigned int old_freq, new_freq;
  56         int ret;
  57
  58         old_freq = clk_get_rate(policy->clk) / 1000;
  59         new_freq = s3c64xx_freq_table[index].frequency;
  60         dvfs = &s3c64xx_dvfs_table[s3c64xx_freq_table[index].driver_data];
  61
  62 #ifdef CONFIG_REGULATOR
  63         if (vddarm && new_freq > old_freq) {
  64                 ret = regulator_set_voltage(vddarm,
  65                                             dvfs->vddarm_min,
  66                                             dvfs->vddarm_max);
  67                 if (ret != 0) {
  68                         pr_err("Failed to set VDDARM for %dkHz: %d\n",
  69                                new_freq, ret);
  70                         return ret;
  71                 }
  72         }
  73 #endif
  74
  75         ret = clk_set_rate(policy->clk, new_freq * 1000);
  76         if (ret < 0) {
  77                 pr_err("Failed to set rate %dkHz: %d\n",
  78                        new_freq, ret);
  79                 return ret;
  80         }
  81
  82 #ifdef CONFIG_REGULATOR
  83         if (vddarm && new_freq < old_freq) {
  84                 ret = regulator_set_voltage(vddarm,
  85                                             dvfs->vddarm_min,
  86                                             dvfs->vddarm_max);
  87                 if (ret != 0) {
  88                         pr_err("Failed to set VDDARM for %dkHz: %d\n",
  89                                new_freq, ret);
  90                         if (clk_set_rate(policy->clk, old_freq * 1000) < 0)
  91                                 pr_err("Failed to restore original clock rate\n");
  92
  93                         return ret;
  94                 }
  95         }
  96 #endif
  97
  98         pr_debug("Set actual frequency %lukHz\n",
  99                  clk_get_rate(policy->clk) / 1000);
 100
 101         return 0;
 102 }
 103
 104 #ifdef CONFIG_REGULATOR
 105 static void s3c64xx_cpufreq_config_regulator(void)
 106 {
 107         int count, v, i, found;
 108         struct cpufreq_frequency_table *freq;
 109         struct s3c64xx_dvfs *dvfs;
 110
 111         count = regulator_count_voltages(vddarm);
 112         if (count < 0) {
 113                 pr_err("Unable to check supported voltages\n");
 114         }
 115
 116         if (!count)
 117                 goto out;
 118
 119         cpufreq_for_each_valid_entry(freq, s3c64xx_freq_table) {
 120                 dvfs = &s3c64xx_dvfs_table[freq->driver_data];
 121                 found = 0;
 122
 123                 for (i = 0; i < count; i++) {
 124                         v = regulator_list_voltage(vddarm, i);
 125                         if (v >= dvfs->vddarm_min && v <= dvfs->vddarm_max)
 126                                 found = 1;
 127                 }
 128
 129                 if (!found) {
 130                         pr_debug("%dkHz unsupported by regulator\n",
 131                                  freq->frequency);
 132                         freq->frequency = CPUFREQ_ENTRY_INVALID;
 133                 }
 134         }
 135
 136 out:
 137         /* Guess based on having to do an I2C/SPI write; in future we
 138          * will be able to query the regulator performance here. */
 139         regulator_latency = 1 * 1000 * 1000;
 140 }
 141 #endif
 142
 143 static int s3c64xx_cpufreq_driver_init(struct cpufreq_policy *policy)
 144 {
 145         struct cpufreq_frequency_table *freq;
 146
 147         if (policy->cpu != 0)
 148                 return -EINVAL;
 149
 150         policy->clk = clk_get(NULL, "armclk");
 151         if (IS_ERR(policy->clk)) {
 152                 pr_err("Unable to obtain ARMCLK: %ld\n",
 153                        PTR_ERR(policy->clk));
 154                 return PTR_ERR(policy->clk);
 155         }
 156
 157 #ifdef CONFIG_REGULATOR
 158         vddarm = regulator_get(NULL, "vddarm");
 159         if (IS_ERR(vddarm)) {
 160                 pr_err("Failed to obtain VDDARM: %ld\n", PTR_ERR(vddarm));
 161                 pr_err("Only frequency scaling available\n");
 162                 vddarm = NULL;
 163         } else {
 164                 s3c64xx_cpufreq_config_regulator();
 165         }
 166 #endif
 167
 168         cpufreq_for_each_entry(freq, s3c64xx_freq_table) {
 169                 unsigned long r;
 170
 171                 /* Check for frequencies we can generate */
 172                 r = clk_round_rate(policy->clk, freq->frequency * 1000);
 173                 r /= 1000;
 174                 if (r != freq->frequency) {
 175                         pr_debug("%dkHz unsupported by clock\n",
 176                                  freq->frequency);
 177                         freq->frequency = CPUFREQ_ENTRY_INVALID;
 178                 }
 179
 180                 /* If we have no regulator then assume startup
 181                  * frequency is the maximum we can support. */
 182                 if (!vddarm && freq->frequency > clk_get_rate(policy->clk) / 1000)
 183                         freq->frequency = CPUFREQ_ENTRY_INVALID;
 184         }
 185
 186         /* Datasheet says PLL stabalisation time (if we were to use
 187          * the PLLs, which we don't currently) is ~300us worst case,
 188          * but add some fudge.
 189          */
 190         cpufreq_generic_init(policy, s3c64xx_freq_table,
 191                         (500 * 1000) + regulator_latency);
 192         return 0;
 193 }
 194
 195 static struct cpufreq_driver s3c64xx_cpufreq_driver = {
 196         .flags          = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 197         .verify         = cpufreq_generic_frequency_table_verify,
 198         .target_index   = s3c64xx_cpufreq_set_target,
 199         .get            = cpufreq_generic_get,
 200         .init           = s3c64xx_cpufreq_driver_init,
 201         .name           = "s3c",
 202 };
 203
 204 static int __init s3c64xx_cpufreq_init(void)
 205 {
 206         return cpufreq_register_driver(&s3c64xx_cpufreq_driver);
 207 }
 208 module_init(s3c64xx_cpufreq_init);